Carotenoids are a class of hydrocarbons consisting of isoprenoid units joined in such a manner that their arrangement is reversed at the center of the molecule. The backbone (skeleton) of the molecule consists of conjugated carbon-carbon double and single bonds, and can also have pendant groups. Although it was once thought that the skeleton of a carotenoid contained 40 carbons, it has been long recognized that carotenoids can also have carbon skeletons containing fewer than 40 carbon atoms. The 4 single bonds that surround a carbon-carbon double bond all lie in the same plane. If the pendant groups are on the same side of the carbon-carbon double bond, the groups are designated as cis; if they are on opposite side of the carbon-carbon bond, they are designated as trans. Because of the large number of double bonds, there are extensive possibilities for geometrical (cis/trans) isomerism of carotenoids, and isomerization occurs readily in solution. A recent series of books is an excellent reference to many of the properties, etc. of carotenoids (“Carotenoids”, edited by G. Britton, S. Liaaen-Jensen and H. Pfander, Birkhauser Verlag, Basel, 1995 hereby incorporated by reference in its entirety).
Many carotenoids are nonpolar and, thus, are insoluble in water. These compounds are extremely hydrophobic which makes their formulation for biological uses difficult because, in order to solubilize them, one must use an organic solvent rather than an aqueous solvent. Other carotenoids are monopolar, and have characteristics of surfactants (a hydrophobic portion and a hydrophilic polar group). As such, these compounds are attracted to the surface of an aqueous solution rather than dissolving in the bulk liquid. A few natural bipolar carotenoid compounds exist, and these compounds contain a central hydrophobic portion as well as two polar groups, one on each end of the molecule. It has been reported (“Carotenoids”, Vol. 1A, p. 283) that carotenoid sulphates have “significant solubility in water of up to 0.4 mg/ml”. Other carotenoids that might be thought of as bipolar are also not very soluble in water. These include dialdehydes and diketones. A di-pyridine salt of crocetin has also been reported, but its solubility in water is less than 1 mg/ml at room temperature. Other examples of bipolar carotenoids are crocetin and crocin (both found in the spice saffron). However, crocetin is only sparingly soluble in water. In fact, of all of the bipolar carotenoids, only crocin displays significant solubility in water.
U.S. Pat. Nos. 4,176,179; 4,070,460; 4,046,880; 4,038,144; 4,009,270; 3,975,519; 3,965,261; 3,853,933; and 3,788,468 relate to various uses of crocetin.
U.S. Pat. No. 5,107,030 relates to a method of making 2,7-dimethyl-2,4,6-octatrienedial and derivatives thereof.
U.S. Pat. No. 6,060,511 relates to trans sodium crocetinate (TSC) and its uses. The TSC is made by reacting naturally occurring saffron with sodium hydroxide followed by extractions.
In Roy et al, Shock 10, 213–7. (1998), hemorrhaged rats (55% blood volume) were given a bolus of trans sodium crocetinate (TSC) after 10 minutes, followed by saline after another 30 minutes. All of the TSC-treated animals lived, while all controls died. Whole-body oxygen consumption increased in the TSC group, reaching 75% of normal resting value after about 15 minutes.Laidig et al, J Am Chem. Soc. 120, 9394–9395 (1998), relates to computational modeling of TSC. A simulated TSC molecule was “hydrated” by surrounding it with water molecules. The hydrophobic ordering of the water in the vicinity of the TSC made it easier for oxygen molecules to diffuse through the system. The computational increase in diffusivity of ˜30% was consistent with results obtained in both in vitro and animal experiments.In Singer et al, Crit Care Med 28, 1968–72. (2000), TSC improved hemodynamic status and prolonged rat survival in a rat model of acute hypoxia. Hypoxia was induced using a low oxygen concentration (10%) air mixture: after 10 minutes the animals were given either saline or TSC. Hypoxemia led to a reduction in blood flow, and an increase in base deficit. Only 2 of 6 animals survived in the control group. The treated group all survived with good hemodynamic stability for over two hours, with a slow decline thereafter.